254 im. G. p. MUDGE ON THE MYOLOGY 



musclc-fibrcs have disappeared from it, leaving only the fascia behind. In Q/cafua 

 ndlplnirca the retrogression in tlie right-hand muscle is more jjronounced than in 

 the left. In Pdttinus, Lurius domicelld (text-iig. 12), Cyanorhdiaphus, Frioniturus, 

 Plfffi/cercus (PI. XXVI. fig. 5), and Calyittorhynchus hankd the area of retrogression 

 has extended posteriorly and become a definite plane of division, which di\ides the 

 muscle into two distinct parts along the length of its anterior two-thirds or more. In 

 Jjorius Jlavo-paUintus (text-fig. 14) the separation is very distinct, but does not extend 

 beyond the anterior fifth. In Strivgops the division only extends to the anterior half. 

 In Pezoporus (Fl. XXIX. fig. 47) the muscle is divided into two parts along its whole 

 length, and the origin of the inner of the two parts exhibits a remarkable contraction 

 similar to that in Eos (PI. XXVI. fig. 1), but it possesses no tendon or tendinous 

 thickening of the fascia. In Poeocephxilus ruppeUi the plane of division does not quite 

 reach to the posterior extremity of the muscle, but the inner portion exhibits at its 

 origin the peculiar contraction of its substance above mentioned, and in addition it has 

 developed a weak and small tendon ; the division of the muscle is not quite so complete 

 on the left as on the right side. In Pceocephalus robustus the right-hand muscle is not 

 divided to a greater extent than the left-hand one in P. ruppelU, and the left-hand 

 one not at all ; otherwise it is as that in P. ruppelU. In Eos (PI. XXVI. fig. 1) this 

 condition reaches its maximum development ; the muscle is very strongly developed, 

 and divided along its whole length into two portions, of which the inner overlaps the 

 outer one posteriorly, and at its contracted origin has developed a well-marked tendon 

 which extends forwards along the outer margin of the posterior half of the muscle. 

 In Nestor' (PL XXIX. fig. 46, se.h.) there appears to be only a single portion present, 

 and this probably represents only the inner portion, since its insertion corresponds to 

 that ; that part of the uro-hypobranchial tendon which represents the insertion of the 

 outer part in other Parrots is free and gives no insertion to any muscle. In Nestor 

 therefore the outer part has probably quite retrogressed. In Lonus (PI. XXIX. 

 figs. 37 &c 38), Eos, and Vini the uro-hypobranchial tendon [u.ten.) has the same 

 relations as that in other Parrots, and the outer portion of the serpihyoideus is 

 inserted to it as in them ; but in addition the antero-outer corner of the muscle 

 is prolonged forwards and forms an independent insertion (ms.), slightly tendinous, 

 on the basihyal between the lateral and anterior portion of the inferior ceratoglossals. 

 In Cacatua (PI. XXVIII. fig. 25), Psittacus (PL XXVI. fig. 3), Sfringops, Eclectus, 

 Calyptorhijnchus, Ptistes, and Conurus cactorum the stylohyoideus is confluent with 

 the serpihyoideus along the length of its posterior half. In Chrysotis (PL XXVIII. 

 fig. 28), Coracopsis (PL XXVIII. fig. 31), Conurus jemlayn, C. holochlorus, Psittinus, 

 Bolborhynchus, Pyrrhura, Pezopiorus (PL XXIX. fig. 47), Psittacula, Poeocephalvs, 

 Palceornis, Platycercus, Nasitenm, Loriculus, Brotogerys, Psepliotus, and Caica the 

 two muscles are confluent only at their origin, or for a very little way in front of that. 



